Ardent D (aka Kurosawa Jr) Winter Camp

[Evil Twin]

LOL, yes that is absolutely hideous Jon. Why is it that your pitiful examples look better than my best efforts...:cry:

But then you should examine Steve Manning's work- had I the time, and if he had the time, I would hire him to build my crossovers....

[Bear]

LOL, yes that is absolutely hideous Jon. Why is it that your pitiful examples look better than my best efforts...:cry:

Yeah. That's why I keep asking for tips....

[1Michael]

I can but offer this pitiful example of one of the wired up low frequency crossover boards...

LOL, yes that is absolutely hideous Jon. Why is it that your pitiful examples look better than my best efforts...:cry:

[5th element]

I suppose no wire would be the best,

We don't use wires in the empire.

[theSven]

I like that expression dueland is not for the faint of heart or week pocket book. But I’m excited to see a CC coming. It all goes back to your earlier post to under promise and over deliver.

[Evil Twin]

Thank you, your Lordship. Is that a solid conductor? Any brand/source preferences? I have given up using Supra wire near my soldering iron.

Usually Alpha wire from a distributor such as Mouser or Digikey. In an ideal world one might use tinned and dipped Litz wire, such as some special OSCO wire I have for high power inductors for power conversion in the reservoir chargers of my Tie Fighter, (using what in local specification would be 105 AWG31 conductors in a bundled Litz matrix).

But at audio frequencies this effort to avoid skin effect is not justifiable, except in some specific cases for inductors acting as series elements for midranges operating at relatively high frequencies, when the secondary roll off effect due to skin effect should be avoided. In this case, foil inductor constructions should be considered... as for a Duelund crossover, where precise control of the roll off characteristic ideally should be maintained to -20dB.


note the construction of the recently completed 1st article tweeter crossover board.





Also, note that this board does not particularly reflect an overall cost optimized build approach, as in some cases more expensive components than necessary were simply used because they were on hand, such as in Fs Zobel impedance control networks. The complexity is due to having an LCR impedance zobel network, an LCR ultrasonic notch filter, and a lower frequency LCR EQ filter, plus having a network concept for which the ultimate slope is 4th order, but only realized over a wide frequency spread with a very controlled increase in attentuation.

Duelund crossovers are not for the faint of heart or weak of pocket book.


In other positive news this week, my local medical specialist was "persuaded" to move me up in his priority queue for the additional bionic implants I have requested, and Friday I had the preliminary medical scans (using the primitive local sector equipment) and we setup the schedule for the rest of the necessary preparations, to culminate in the bionic restoration in mid June - the 16th in the local calendar.

This timing will allow me to complete a cargo run to the outer rim next week - loading a variety of items, including the new SawStop table saw, was nearly finished this weekend, only a couple of very high value items (worth more than the transit shuttle) are pending loading on the departure date of this Thursday.

Matters are proceeding better than I had foreseen before this week... one must be prepared to seize opportunities as they arise...

Next today will be completing the midrange crossover test article construction.

These two boards will be used for other system evaluation that are currently planned, as the transfer function and characteristics will not change for the midrange and tweeter, only for the different woofers.

In preparation are test concepts for a small CC using the Anarchy 558, and a larger CC or tower using the Anarchy 708. All would use the same midrange/HF concept with Duelund transfer function crossover.

The PuriFi woofers are another possibility- though for now, they are planned mainly for the NatlieP Ultra. Still, preparing an equivalent design should be a fairly simple task, and test enclosures are partially constructed. Now it may be a race to complete the heavy work for test setups prior to my bionic update procedure; follow that, I will have several weeks off when lighter work may be accomplished.

After that, cargo runs to the outer rim must re-commence...

[Bear]

I suppose no wire would be the best, but I have rarely found that to be possible.

In this and other recent builds, I use a mix of wire gauges depending on the length of wire run and mechanical support required- so I have spools of AWG12, AWG14, and AWG16.

I expect that for smaller boards one could completely justify just settling on AWG16 or 14.

Thank you, your Lordship. Is that a solid conductor? Any brand/source preferences? I have given up using Supra wire near my soldering iron.

[Evil Twin]

What type of buss wire are you using in the crossover? I have been attempting to avoid using any, but I think that I have met my match.

I suppose no wire would be the best, but I have rarely found that to be possible.

In this and other recent builds, I use a mix of wire gauges depending on the length of wire run and mechanical support required- so I have spools of AWG12, AWG14, and AWG16.

I expect that for smaller boards one could completely justify just settling on AWG16 or 14.

[Bear]

A ridiculous schedule for my service to the Empire (including all this last three day weekend) has slowed efforts substantially... I can but offer this pitiful example of one of the wired up low frequency crossover boards...


[ATTACH=CONFIG]30306[/ATTACH]




It is fortunate that I dispensed of Palpatine many years ago, or I am sure I would be feeling his wrath...

What type of buss wire are you using in the crossover? I have been attempting to avoid using any, but I think that I have met my match.

[JonMarsh]

A ridiculous schedule for my service to the Empire (including all this last three day weekend) has slowed efforts substantially... I can but offer this pitiful example of one of the wired up low frequency crossover boards...







It is fortunate that I dispensed of Palpatine many years ago, or I am sure I would be feeling his wrath...

[Scottg]

^what he said.

[5th element]

That looks much better!

[Evil Twin]

progress...

More measurements, more circuit adjustments, and more parts ordered, and first article board construction started.

I believe that means more progress....

[5th element]

I actually like the look of this but it's not metal and isn't anywhere near as interesting as the ceramic dome.

https://hificompass.com/ru/speakers/...ss-dx20bf00-04

[5th element]

I've no idea what neo tweeter I'd use but surely there must be something with excellent distortion performance if you don't need it to cross low. I'd say go with any number of available models but the off axis wouldn't be exactly the same.

I'm aware that the Dueland approach dictates driver bandwidths but what is it supposed to be giving you in return for its intrinsic limitations? A peak in the presence region wouldn't seem worth it.

I'm absolutely baffled why tymphany used a gigantic face plate diameter for the da25. What we want is smaller than 104mm for progress, not bigger. Such a ridiculous design choice. At least if you need bigger incorporate a waveguide.

[Evil Twin]

Do note what the response requirements are for a Duelund crossover- it places bandwidth and level demands far different from crossovers like the 3rd order quasi-LR3 Wavecor Ardent crossover.


If you could point out a small form factor tweeter with the same low distortion and wide smooth off axis response as the DA25 in a similar price range, I would be very interested, though at this point it is late in the game for changing this build, since the cabinets are constructed. A wide range of driver testing completed earlier this year has failed to turn up such a candidate, even when examining competitors in the $400 range. It is disappointing in some respects to now have such a large collection of expensive tweeters, many with Beryllium domes, that are mostly out performed by a $50 tweeter.

Also, I should note that this is an early look at the development concept and there have already been a number of component updates in the process of finalizing component selections and re-checking simulations. Crossover construction will begin in earnest when the next $700 batch of components arrives. Fortunately, many are already on hand.

[5th element]

Crossover looks good overall!

The "bump" near 2.1 kHz is a little worrying though. (..this is about the area where I typically experience a trace of "hardness" subjectively with this sort of result.)

The phase angle near 50 Hz isn't kind, but the Impedance isn't low at this point so it shouldn't be difficult on the amplifier.

Yeah I would definitely lower the mid/tweeter xover point to put the bump in the mids response into the knee of the mids low pass to help get rid of it. And use a notch, if needed, to smooth it out out completely.

Probably cross around 2.5kHz or so.

It seems a waste to use a tweeter with such a gigantic faceplate if you aren't going to make use of its ability to cross low. Should really just use a small neo jobby and get the c2c down. Especially if you want to cross at ~4kHz.

I would imagine response smoothness and power response would both improve taking the tweeter right down to 2kHz. Then you'd be using the mid more as a filler driver.

That bump at 2.1k would melt my hyperacusis ears right off.

[Evil Twin]

75 ohms.

[chrisn]

+1 Looks good! Hard to read, is R4 a 75 or .75 ohm?

[Scottg]

Crossover looks good overall!

The "bump" near 2.1 kHz is a little worrying though. (..this is about the area where I typically experience a trace of "hardness" subjectively with this sort of result.)

The phase angle near 50 Hz isn't kind, but the Impedance isn't low at this point so it shouldn't be difficult on the amplifier.

[Evil Twin]

First Article test crossover design...

With in cabinet measurements, it is now possible to move from experimental POC crossover designs using previous data, to a true first article candidate/proposal crossover implementation.


To review the crossover target concept... the Duelund crossover is based on a single transfer function for all three elements defined and matched mathematically to produce a response that tracks in phase across the whole audio range with but a single phase rotation. If the aleph gain coefficient is reduced beyond a certain point, the midrange part disappears and the result is an LR4. Raising the aleph coefficient increases the level and bandwidth of the midrange element, and the only other data point needed for definition is the center frequency.




Doing this in practice, or coming adequately close to doing this is demanding of both the driver capabilities and the crossover, and both must be chosen carefully, in interrelationship, and in consideration of the usable bandwidth of the drivers and maintaining the expected response down to -20 dB.




In this case, it is also desired to implement a slight voicing down tilt. Experience with the Wavecor Ardent has shown this to be subjectively preferred for stereo reproduction with the majority of recording, when considering a speaker with wide off axis response.







The impedance character must be carefully managed, and in this case the target of 4 ohms or better is met.




The midrange and tweeter sections are quite close to the initial POC crossover done with data from different enclosures, so most of the already purchased components can be used.

It is time to prepare a preliminary BOM and the initial test crossover boards - that will begin today.

[Evil Twin]

Key measurements completed

Some additional measurement requirements on the test cabinet builds have been fulfilled using the new turntable so that now we may proceed from Proof Of Concept crossover design study to first article test build crossover design...




AS168 Polar set, 0 - 60 degrees



The AS168 behaves similarly to the AS190, in that the response profile produces the effect on an appropriate narrow baffle resembles a conventional driver mounted infinite baffle. This has some clear positive implications for filter design and inductor size and DCR issues, though it impacts the facility of implementing something like a 2.5 or 3.5 way approach.

The uniformity of response through the first breakup peak in this frequency range is only matched by the AS190 in my experience. The expectation of this characteristic is the principle reason this driver was chosen as a candidate for the Duelund style implementation.



RS52AN Polar set, 0 - 60 degrees





DA25

[Evil Twin]

One would be even more excited were it not for the overall environment and uncertainties.

But it will be time for some measurements soon... first will be capturing the midrange and tweeter on these specific baffles. The test configuration is undergoing some updates right now.

next in the construction agenda is finalizing the design of the baseplates and footers...


The intriguing part is seeing how well the Duelund concept works out with a three way configuration using all dome drivers...

[5th element]

Things are getting exciting! I do like the visual aspect of that line of drivers.

[Evil Twin]

The design of the AS168 does not lend itself to using threaded inserts- this is due to the relatively narrow "flange" and proximity of the mounting holes to the minimum cut out hole.


This picture illustrates the problem, when pilot holes for #8 stainless wood screws are drilled.




In fact, I would not even consider building a cabinet for these woofers using a softer conventional material such as MDF.


After the full depth of the pilot holes are completed, the prepared cables are attached via quick connects for now,






And woofers mounted, and the cabinet moved back into the "storage" position while other work is done...

[Evil Twin]

Caution: that small inset "lip" (on the tweeter in particular) is going to cause some diffraction which typically changes the freq. response with changes in spl. ops:

Maybe a galvanized sheet shim to get it flush with the baffle?

It actually 'is" flush with the baffle- the photography is misleading... for reasons I do not understand. BTW, this is a modified version of the tweeter with a double thick plate.

[Scottg]

Caution: that small inset "lip" (on the tweeter in particular) is going to cause some diffraction which typically changes the freq. response with changes in spl. ops:

Maybe a galvanized sheet shim to get it flush with the baffle?

[Evil Twin]

internal wiring

The wiring concept for this design study is quite simple, and modified from some past practice due to Cardas discontinuing my favorite intra-cabinet midrange and tweeter wiring cable.

Main input wiring to crossovers will be done with Kimber 12tc, the midrange and tweeter drivers with Kimber 8tc, and the woofers with Cardas Speaker 101.





The tweeter banana plugs include a screw on collar, but getting this sufficiently tight for a long term connection is not really feasible, especially not for tinned conductors. It is more direct to simply solder the leads to the BP connectors.





The resulting connection when plugged in is quite secure...





From this point, mounting the drivers is quite straightforward and installation with the inserts highlight the advantages to this extra work.





From this point, the next step will be the woofer mounting. Note that this design study cabinet was prepared specifically for the ability to test both the Accuton AS168 and the new PuriFi woofers; as such, some compromises in the configuration for woofer rebates had to be made, as regards the rebate diameter and depth, to work with either driver type, and testing the PuriFi woofers will require additional spacer which Steve Manning has fabricated.

[Evil Twin]

Mechanicals...

These past few weeks have made finding project time and focus more difficult than usual. However, some progress can be reported, for those few that may be interested in these times...

The focus now is preparing driver mounting hardware and mounting some drivers for initial tests...


Simple tasks such as drilling the threaded insert holes and boring them out slightly over size (2/64") in consideration of the hardness and density of the wood being used.




the same concept is used for both front and rear inserts, in order to avoid issues with the very hard bamboo boards or maple ply. The inserts have a small dot of non-drip 30 minute epoxy applied before assembly, and the overall results were as expected, and most satisfactory.





As predicted by the 3D assembly drawings, the banana plug-ins on the back of the DA25 tweeter present a slight clearance problem for the overall depth available with the 3" thick front panel. As planned, this is addressed by the use of a 1" Forstner bit.





If a drill press were available and not in storage in the outer rim, a larger bit would be feasible to use in one operation. But for handheld usage, it was deemed advisable to take a different path... first with two passes removing 3/8" of material...





Then a "second pass" for the final configuration.

[Scottg]

It's just resin impregnated wood/fabric under pressure. (..and you can always DIY this - a fair number of Youtube videos on this with carbon fiber.)

Germany has thin ply compressed: Panzerholz (..tough to get here in the US, whereas we have several sources of paper/canvas/fiberglass)

https://www.delignit.de/en/brands.html?ma=0

Other brands to search for: Micarta, Garolite, Ultrex, Richlite, Paperstone..

[ergo]

Very nice implementation of turntable and following the KISS principle all the way
That Lazy Susan looks 100% same as the ones I got from Alibaba and which is sandwiched between mine.

Btw, if anyone on EU side knows a source for this type/size of phenolic on EU side I would be greatful. I've been looking but no luck this far... probably don't know the keywords to look for. I have some ideas for tool improvements where this stuff would be great.

[Evil Twin]

Fabrication in progress

Some reasonable progress has been made today on a variety of projects, including the Ardent D.


The test turntable is being built with the basic concept of "rapid prototyping" and in consideration of the planned manual operation via Force Push.

Marine epoxy is the closest substance to "Force Glue" and was used liberally as needed. The upper plate is 1/2" tooling phenolic, and the base was fabricated from 19mm BB ply




Instead of laser or machine engraving the preferred tool of the current POTUS was used for calibration purposes, a black Sharpie.








A secondary plate will be added for support so that the front panel can be centered in the turntable circle.


The baseplates were also cut out today from 1/2" tooling phenolic, from the preferred color... this material is often used for secondary armor in Tie Fighters and Bombers, due to it's high density and strength.

[chrisn]

Looks good ET..

[Scottg]

No we had not discussed the idea ..... certainly can be done if there was enough interest.

https://vimeo.com/199557072

[Bear]

The Maple and single-ply bamboo contrast very nicely with each other.

[Evil Twin]

Smuggling operations for the Imperium to the outer rim have not been able to resume.

On the other hand, this freed up some time for finishing on the second cabinet, which is nearly complete...






Additional materials for test and calibration fixtures and crossovers have arrived, in spite of the medical embargo...

[JonMarsh]

Thanks for sharing what you built! Gives some further food for thought...

[ergo]

I've done just that with my turntable... somehow I can't find a picture before I assembled it, but there are 6mm wide and about 25mm long 'stripes' milled every 5degrees and then the 3D printed spring acts as a stop to dial in an angle.

PS. The plastic dial is removable so my kid can use it free rotating to tune drums...
The top plate is not round partially because my CNC work area was not wide enough to make a circle, but also because one does need some extra room from center to back but never to the sides really.

[Steve Manning]

I'm sure that you guys have thought about this, but accurate angle markings on a lazy susan can be done much more precisely with a CNC, especially to provide a positive lock between the top and bottom plates. Have you considered having a speaker measurement product as a standard offering, in addition to the speaker kits themselves?

No we had not discussed the idea ..... certainly can be done if there was enough interest.

[Bear]

There's a lot of driver testing to be done, and I just ordered another lazy Susan bearing set (had to toss the older turntable setups two years ago, they got rained on, and MDF doesn't like that at all... new ones will use phenolic- already on hand...


Steve just built some test ring adapters so ET can evaluate the PuriFi woofers in these cabinets and get design data, too. I've heard through the grapevine that they arrived yesterday... I don't doubt they'll perform well, but I'm more curious about the application in a NatalieP update, and unusual baffle layout ET's come up with based on Edge simulations and some specific performance targets... seeing how that measures should be interesting, too... I may have to get involved and lend a hand.

I'm sure that you guys have thought about this, but accurate angle markings on a lazy susan can be done much more precisely with a CNC, especially to provide a positive lock between the top and bottom plates. Have you considered having a speaker measurement product as a standard offering, in addition to the speaker kits themselves?

[JonMarsh]

This issue of ferrous metals in the signal path is an old one- but still not widely considered.

It was a consideration in the selection of binding posts for the early Avalon designs, and when Charlie founded Ayre Acoustics and I was working with him on an early preamp design, we had to go over component materials carefully- turns out some SMD resistors use nickel in the conduction path, and that has an effect, something like a bit of hysteresis, with a bit of fuzz or tizz added to the presentation.

And while I don't blink at buying Cardas binding posts for myself (just look at the retrofits I've done on my Cambridge amps, even the 840W power amp), On the forum I'd rather find and suggest something 95% as good for 20% of the price when possible... lord only knows these three way crossovers will never be cheap, but things like the Obligatto caps help a lot with the price/performance ratio. Otherwise it just gets crazy...

Well, one could argue it's crazy anyway, trying to build mid budget speakers and keep the performance up and the price down.

There's a lot of driver testing to be done, and I just ordered another lazy Susan bearing set (had to toss the older turntable setups two years ago, they got rained on, and MDF doesn't like that at all... new ones will use phenolic- already on hand...


Steve just built some test ring adapters so ET can evaluate the PuriFi woofers in these cabinets and get design data, too. I've heard through the grapevine that they arrived yesterday... I don't doubt they'll perform well, but I'm more curious about the application in a NatalieP update, and unusual baffle layout ET's come up with based on Edge simulations and some specific performance targets... seeing how that measures should be interesting, too... I may have to get involved and lend a hand.

[Steve Manning]

Yep, they are rhodium plated copper. I was looking at Cardas binding posts, but these seemed to offer much of the same for a lot less and passed the intel on to ET.

[Scottg]

With the knowledge from Purifi thread it appears those amps at least don't like ferrous/magnetic binding posts. Just out of curiosity are these fully non magnetic?
My Jantzen ones were ok, but my fried had ones where the washers were ferrous, so he replaced those on his OLA project.

The nut (and the screw in the post) looks like brass, the rest should be Copper with Rhodium plating.

Alternatively, (like the WBT-0708 Cu, but less expensive):

https://www.amazon.com/EIZZ-EZ-301-Speaker-Connector-Terminal/dp/B074DY6QZ9

[xsilverjag]

Awesome Work! I have enjoyed reading these updates during my quarantine.

[ergo]

With the knowledge from Purifi thread it appears those amps at least don't like ferrous/magnetic binding posts. Just out of curiosity are these fully non magnetic?
My Jantzen ones were ok, but my fried had ones where the washers were ferrous, so he replaced those on his OLA project.